Reciprocating floor conveyors have been used for several years in van bodies and in trailers for unloading cargo. These conveyor systems are widely used in va bodies and trailers for transporting bulk material such as ground plant material for animal feed, saw dust, wood chips, bark, and plant material for human consumption. Reciprocating floor conveyors are also used in stationary installations to convey material. Stationary reciprocating floor conveyors are used to meter bulk material for a variety of purposes such as refuse sorting and feeding solid fuel into a boiler. The conveyor systems include a plurality of parallel floor slats. Each floor slat is mounted so that it can slide back and forth in a direction parallel to its long axis. The floor slats are reciprocated back and forth in a sequence that results in cargo supported on the floor slats being conveyed toward one end of the floor slats.
Several different drives and drive systems have been employed in reciprocating floor conveyors to reciprocate the floor slats back and forth. A commonly used drive system includes three hydraulic cylinders that move all the slats simultaneously to the rear toward a rear discharge carrying cargo with them. The first cylinder is connected to every third floor slat. The second cylinder is connected to all the floor slats that are adjacent to a common side of the floor slats attached to the first cylinder. The third cylinder is attached to the floor slats that are between the floor slats driven by the first cylinder and the floor slats driven by the second cylinder. The first, second and third cylinders are activated one at a time to move every third floor slat forward and away from the rear discharge without moving cargo forward. The floor slats do not carry cargo forward because two thirds of the floor slats that are stationary, while one cylinder moves one third of the floor slats forward, hold the cargo. The second cylinder moves the floor slats connected to it forward while the floor slats connected to the first and third cylinders remain stationary. The third cylinder then moves the floor slats connected to the third cylinder forward while the floor slats connected to the first and second cylinders remain stationary. The above procedure is then repeated to move cargo through the rear discharge opening. The procedure continues to be repeated until all the cargo is discharged. The conveying cycle can be stopped and restarted as required to control the rate of material discharge.
The floor slats that are currently used are generally extruded aluminum members. Each floor slat has a generally horizontal upper section, spaced apart sides that extend downwardly from the bottom of the horizontal upper section and generally horizontal flanges on the lower edges of each side wall that extend inwardly toward each other. The floor slats are supported by bearings made from a low friction material. The bearings are attached to guide beams and cross beams. A guide beam extends substantially the length of each floor slat and is fixed to and supported by a plurality of cross beams. The cross beams are an integral part of the frame of the trailer or van body. The practice is to employ a bearing at each location where a guide beam crosses a cross beam. Trailers with reciprocating floor conveyors that are currently manufactured have about nine hundred to over twelve hundred separate floor slat support bearings.
Each of the current bearings has an upper horizontal bearing surface that contacts and supports the bottom surface of the generally horizontal upper section of a floor slat. Each bearing also has side flanges that can contact the upper surface of the generally horizontal flanges on the lower edge of each side wall of the floor slats to prevent the floor slats from lifting up and away from the bearings.
The bearings are exposed to mud, dust, sand and gravel, and liquids that are thrown up from road surfaces. These materials that are thrown up from the road surface tend to stick to the bottom surface of the generally horizontal upper section of the floor slats between the bearings and to work in between the floor slats and the upper horizontal bearing surface of each bearing when the floor slats are reciprocated back and forth. This foreign material between the floor slats and the bearings increases the force required to reciprocate the floor slats and increases the rate of wear on the floor slats. In time floor slats can wear through where their horizontal upper section is in contact with and supported by a bearing. Wear of the contact surfaces between the horizontal upper section of a floor slat and a bearing can lower the floor slat and allow the sides of the floor slats to contact the cross beams or a bearing surface on the portion of a bearing that is between the cross beams and the sides of a floor slat. Such contact will result in wear on the sides of the floor slats. Wear on the sides of the floor slats will decrease the strength of the floor slats and may in time destroy the floor slats.
The time required to install nine hundred to twelve hundred bearings during manufacture of a floor conveyor is significant. Depending upon the specific design it may be necessary to manually align each floor slat with each bearing during installation of the floor slats. These time consuming tasks increase the cost of manufacturing a reciprocating floor conveyor and also increase the time required to repair a reciprocating floor conveyor.
The bearings that are currently used may slide back and forth a short distance relative to the guide beams and the cross beams. Such movement of the bearings relative to the guide beams generally does not cause any significant wear or damage. However, bearings which are able to slide around on the guide beams and cross beams do not positively position and hold floor slats as well as may be desired. Improper positioning of floor slats will result in improper sealing between adjacent floor slats and loss of cargo. The improper positioning of floor slats may also result in damaged floor slats.